Catalyst for purifying organic nitrogen compound-containing exhaust gas and method for purifying the exhaust gas

A catalyst composition formed by mixing (a1) copper oxide particles represented by the compositional formula CuOx, where 0.45≦×≦1.1, and wherein the copper oxide particles are CuO particles or a mixture of CuO and Cu2O particles, (a2) particles of a zeolite, and (a3) inorganic oxide particles selected from the group consisting of silica and titania having, carried thereon, one or more precious metals selected from the group consisting of Pt, Pd, Ru, Rh, Ir, and an alloy thereof,

• wherein a weight of the copper oxide particles relative to a sum of a weight of the copper oxide particles and a weight of the zeolite is in a range of 0.1 wt. % to 40 wt. %,
• wherein the zeolite is selected from the group consisting of mordenite, MFI-type, and β-type zeolites, and the zeolite is one or more of zeolites of a proton type, or is one or more of zeolites ion-exchanged with a Group 8 metal, a Group 9 metal, a Group 10 metal or a Group 11 metal, and a SiO2/Al2O3 molar ratio of the zeolite is 5 to 50, and
• wherein the catalyst composition converts about 80% or more of the nitrogen in organic nitrogen compounds, ammonia, or a combination thereof in an exhaust gas to N2 at a reaction temperature of 350° C.